Fiscal federalism efficiency influence on local entity operations has recently gained tremendous recognition. However, the most surmountable challenge faced by majority developed-developing nations localities, is how to sustainably attain that fiscal credibility. Some theory-research-practice triangulation segments claim that fiscal federalism efficiency is easily achievable if entity budgetary behavior is well-managed. Others; notably those in the African setting, assert it is impractical without involving ethnicity-tribalism considerations. This research was an in-depth survey of budgetary behavior-fiscal federalism linkages in some Ugandan (East Africa)-based entities considering ethnicity-tribalism triangulation as a mediating factor. Its findings reveal that much as process control and manpower; key budgetary behavior attributes predict fiscal federalism efficiency, its other construct administrative machinery does not. Besides, the anticipated mediator; ethnicity-tribalism practices in the country’s northern-eastern regional entities, plays no intervening role. Theory-literature-practice implications and future research path are systematically provided.